The present invention pertains to a low-inertia presser device for sewing machines which is effective in maintaining positive control of a workpiece being advanced by the combined efforts of said machine's presser foot and feed dog. Such control maintains the base of the presser foot in positive contact with the workpiece during displacement of the feed dog above the needle plate, and eliminates the possibility of movement of the workpiece other than rectilinearly along the sewing axis.
Devices for controlling presser elements in sewing machines are known to those conversant in the sewing art, such as the teachings disclosed in British Pat. No. 161,487 and U.S. Pat. No. 2,712,803. Although the devices of these patents have satisfactorily performed their intended functions, they have not provided what is considered as a low-inertia device for control of a machine's presser foot. One of the known types of presser control devices utilizes an elongated member that is acted on by a leaf spring and, being operatively connected to the machine's presser foot, has the disadvantage of additional inertia of said spring which, because of its size, has a substantial moment of inertia.
Another known type of presser control which utilizes an arm for supporting the machine's presser foot applies what is considered a considerable amount of weight at the location of the pressure media on said arm, and with the guide for the latter not being sufficiently precise so as to provide positive and repeated accuracy of movement of said presser foot.
The presser foot control according to the present invention eliminates the disadvantages associated with the presser devices of the prior art by providing a device which minimizes the inertia of the moving parts, i.e. the presser foot, the bar which supports said presser foot, the coil spring, and its supporting sleeve operatively associated with said bar. Additionally, the device of the invention is effective in maintaining a workpiece in positive alignment with the direction of its feed and in causing a desirable release and rotation of the presser arm around a vertical axis.
An object and advantage of the invention is that of causing the underside of the presser foot to accurately and consistently track the movement of the feed dog during the latter's movement above the needle plate so as to effect controlled movement of a workpiece in a straight line along the sewing axis.